Research Article The Effects of Controlled Drainage on N

Research ArticleThe Effects of Controlled Drainage on N Concentration andLoss in Paddy Field

Bin Lu12 Guangcheng Shao2 Shuangrsquoen Yu2 Shiqiang Wu1 and Xinghua Xie1

1State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210029 China2Efficient Irrigation and Drainage and Environment of Agriculture Water and Soil South Area Key Laboratorythe Ministry of Education College of Water Conservancy and Hydropower Hohai University Nanjing 210098 China

Correspondence should be addressed to Bin Lu 370568102qqcom

Received 13 October 2015 Accepted 21 March 2016

Academic Editor Yuangen Yang

Copyright copy 2016 Bin Lu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

To relieve the situation of the agricultural nonpoint pollution (NPS) in south and east China paddy field controlled drainage(PFCD) is applied as an important and efficient approach to agricultural water management A series of PFCD tests at four majorgrowth stages of rice were conducted by use of 18 lysimeters Concentration of ammonia nitrogen (NH

4

+-N) and nitrate nitrogen(NO3

minus-N) in surface and subsurface paddy water was observedThe results indicated that the concentration of NH4

+-N andNO3

minus-N in paddy water declined with the persistence of a waterlogged condition Compared to traditional drainage PFCD reduced Nloss in surface water by 956 787 596 and 874 at the stage of tillering jointing-booting heading-flowering and milkingrespectively It should be noted that loads of N losses in surface water increased on the fourth day after waterlogging at the jointing-booting and milking stage and surface water exhibited higher N concentration on the first day after waterlogging at each stageTherefore paddy field surface water drainage should be avoided in these periods

1 Introduction

Field drainage is widely known as an essential measure toensure that crops achieve high and steady production How-ever unreasonable field irrigation and drainage manage-ment present several problems as well For example excessdrainage leads to the mass flow of agriculture pollution intorivers and lakes Furthermore nitrogen (N) and phosphorus(P) runoff and drainage from paddy fields are major sourcesof nonpoint source pollution (NPS) in south and east China[1ndash3] In severalmajor lakes such asTaihuLakeDianchi Lakeand Chaohu Lake eutrophication has become increasinglysevere [4ndash7] With regard to problems of water shortage andwater environment deterioration controlled drainage (CD)has been identified as an efficient approach to agriculturalwater management in humid and arid regions [8ndash10]

Paddy field controlled drainage (PFCD) is a highly effi-cient drainage pattern that uses the institution of outfall tocontrol field water discharge and elevate the level of farmditch as well as achieving water saving and pollution reduc-tion [11 12] This pattern is different from the conventional

pattern of paddy field drainage Industry practice showsthat paddy fields can retard and store floodwater duringmajor flood periods Furthermore paddy fields not only saveirrigation water and improve the utilization of rainwater butalso alleviate the region pressure of flood protection [10 11]

Controlled drainage which is also called drainage watermanagement (DWM) has been used for several years inNorth Carolina Florida and other locations [9 13] In thecontrolled drainage situation the flow lines are shallowerthan in the uncontrolled system and the water table is main-tained at a shallower depth by a control structure whichreduces deep percolation below the root zone by reducinghydraulic gradients and increases capillary upflow as evapo-transpiration depletes soil water in the root zone [8] Numer-ous studies have shown that CD could reduce annual trans-port of total N in the field by 40ndash50 and total P by 35ndash45 [14ndash17] Annual CD could reduce approximately 30ndash60 of water volume compared with conventional drainage[18ndash20] One the one hand CD can reduce total leach-ing rate from lesswater drainage on the other hand the rise of

Hindawi Publishing CorporationJournal of ChemistryVolume 2016 Article ID 1073691 9 pageshttpdxdoiorg10115520161073691

2 Journal of Chemistry

Table 1 Physical and chemical characteristics of topsoil (0ndash30 cm layer) in lysimeters

120579119899

120588119887

Porosity pH Organic matter Total N Available N Total P Available P() (gcm3) () (mdash) (gkg) (gkg) (mgkg) (gkg) (mgkg)2528 146 4497 697 2188 09048 2765 032 125Note 120579119899 and 120588119887 represent field moisture capacity and soil bulk density respectively

subsurface water level can prompt soil denitrification whichthen decreases the concentration of nitrate nitrogen

The PFCD technology was discovered by Chinese schol-ars in the 1990s and several experimental studies and fieldpractices have been conducted constantly in rice-plantingregions Zhang et al [21] studied the transport and loss ofnitrogen in a drainage paddy field Luo et al [22] and Jia et al[23] conducted field experiments on the effects of drainagecontrol on salt and water balance in the Yinnan irrigationdistrict Xiao et al [24 25] examined the changes in N andP of flooded paddy water systems and obtained the optimaldrainage time at each stage of growth All the results con-cluded that PFCD plays a significant role in water conserva-tion and nonpoint source pollution reduction

Two important factors for PFCD are surface water leveland waterlogging duration When the paddy surface waterlevel is too deep or when the duration of waterlogging is toolong a waterlogged disaster can occur which may then causeplant growth retardation and yield reduction On the con-trary pollution reduction and water conservation cannot beachieved when waterlogging duration is too short To achievecomprehensive benefits from environment and economicresources we must assess surface water depth flooding timeleakage intensity and other factors [26 27]

This study emphasized the environmental benefits ofdeliberate water resources utilization The paper showeddynamic changes in N concentration in surface and subsur-face paddy water analyzed the effects of leakage intensityand N leaching calculated loads of N losses through surfacedrainage and demonstrated the effects of pollution reductionand water saving through PFCD

2 Materials and Methods

21 Experimental Site This study was conducted in an exper-imental field at water-saving and agroecological experimentalplot located in JiangningCampus ofHohaiUniversity JiangsuProvince of China (Nanjing latitude 31∘571015840N longitude118∘501015840E 144m above sea level) The region has a subtrop-ical humid monsoon climate zone with an average annualevaporation of 900mm and yearly average temperature of157∘C and themaximum andminimum air temperatures are430∘C and minus140∘C respectively The mean annual rainfall is1021mm of which more than 60 of precipitation falls in therainy season and the precipitation is concentrated in May toSeptemberThe number of frost-free days is 237 per yearThetemperature precipitation and evaporation were recordeddaily by an automatic weather station (ICT Australia) in theexperimental plot

The area has been 5 years of rice-wheat rotation systemThe soil in the area is a typical permeable paddy soil The

topsoil was 0ndash30 cm in lysimeter with pH value of 697 soilbulk density was 146 gcm3 soil porosity was 4497 andfield capacitywas 2528Characteristics of topsoil are showninTable 1There are 32 fixed lysimeter test-pits (28with closedconcrete bottom 4 without bottom) with specifications forthe length times width times depth = 25m times 2m times 2m in the experimental field Those lysimeters layouts were divided into twogroups of 16 each We only employed 18 of them in thisresearch shown in Figure 1(a) Underground gallery anddrainage system are built between the two groups and amobile canopy is equipped on the ground

An integrated irrigation-drainage system (IDS) wasinstalled at the experimental field For the irrigation systemwater was supplied from an underground reservoir to everytest-pit through pipelines and the accuracy of irrigationwater volume is controlled by a computer by controlling theelectromagnetic flow valves (see Figures 1(a) and 1(c)) Watertable was changed by raising or lowing the height of a floatvalve for each treatment When the ponded water depthdropped to the lower water level irrigation water was addedwith auto-irrigation system until the upper water level limitwas reached For details of water table control structures seeFigure 1 in [28] The drainage system is located in subsurfacebelow the ground path in the middle of the test-pits (seeFigures 1(a) and 1(b)) Groundwater in the test-pits can bedischarged through artificial drainage which can controldrainage time and water volume and facilitate collection ofgroundwater samples

22 Experimental Design The variety of rice used in the2010 experiment was Japonica riceYangjing 4038 To performpaddy field water level management under different floodingconditions we designed a series of tests at the four majorstages of rice growth (tillering jointing and booting headingand flowering and milky stage in such order) The paddyfield water levels rice growth stages and controlled drainageperiods are summarized in Table 2

Eight waterlogging and controlled drainage treatments(W1ndashW8) and one treatment for comparison (CK) were usedin the experiment each with two reduplications Waterlog-ging treatments were performed in lysimeters with a closedbottom whereas comparative treatments were performed inlysimeters without a bottom Two leakage rates (2mmd and4mmd) were designed under the same flooding conditionin each stage The paddy field waterlogging process was sim-ulated after one occurrence of intensive rainfall in differentperiods The irrigation program used on comparative treat-ments was based on controlled irrigation which is an irriga-tion program for water saving [28 29]

Agricultural fertilization was conducted three times dur-ing the period of rice growthThe fertilizers appliedwere base

Journal of Chemistry 3

W1a

W1b

W2aW3aW4aCKa W8a W7a W6a W5a

W2bW3bW4bW5bW6bW7bW8bCKb

Water pipelineElectromagnetic flow valve device

Control and operationroom

Undergroundreservoir

Collecting well

Two-way valve

Underground gallery and drainage system

Without bottom Closed bottom

NS

S

Watertank

Subsurface water table observation pipeTemperature and moisture sensor (in soil)

N

N

Drainage valve

20m 25m

Fixed lysimeter test-pit (length times width times depth = 25m times 20m times 20m)

(a)

(b) (c)

Figure 1 (a) Schematic diagram of irrigation-drainage system (IDS) and test-pits distribution Water was supplied from an undergroundreservoir to every test-pit through pipelines (b) Underground gallery and drainage system (c) Lysimeter test-pits Inside the yellow box isthe electromagnetic flow valve device

Table 2 Design of PFCD water level and controlled periods in 2010

Growth stage Tillering stage Jointing-booting stage Heading-flowering stage Milking stageGrowth date(monthday) Jul 05simAug 05 Aug 06simAug 26 Aug 27simSep 09 Sep 10simSep 22

Control date(monthday) Jul 19simJul 28 Aug 14simAug 23 Aug 30simSep 08 Sep 12simSep 21

Surface water level orsubsurface water tabledepth (mm)

W1 120 (2mmd) minus300sim30 minus300sim30 minus300sim30W2 120 (4mmd) minus300sim30 minus300sim30 minus300sim30W3 minus200sim20 250 (2mmd) minus300sim30 minus300sim30W4 minus200sim20 250 (4mmd) minus300sim30 minus300sim30W5 minus200sim20 minus300sim30 250 (2mmd) minus300sim30W6 minus200sim20 minus300sim30 250 (4mmd) minus300sim30W7 minus200sim20 minus300sim30 minus300sim30 250 (2mmd)W8 minus200sim20 minus300sim30 minus300sim30 250 (4mmd)CK minus200sim20 minus300sim30 minus300sim30 minus300sim30

Note bold types indicate paddy field controlled drainage treatments at different stages the left numeral is paddy water level and the numeral in parenthesesis drainage intensity under control Minus sign represents subsurface water table depth


00

05

10

15

W1W2

Date

06

04

02

00

Jul 19 Jul 22 Jul 25 Jul 28

NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(a)

Date

00

03

06

09

W3W4

Aug 14 Aug 17 Aug 20 Aug 2312

08

04

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(b)

Date

00

02

04

06

W5W6

Aug 30 Sep 02 Sep 05 Sep 08 18

12

06

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(c)

Date

00

07

14

21

W7W8

Sep 12 Sep 15 Sep 18 Sep 21 12

08

04

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(d)

Figure 2 Dynamic changes of NH4

+-N and NO3

minus-N concentration in surface water (a) Tillering stage (b) Jointing-booting stage (c)Heading-flowering stage (d) Milking stage

fertilizer (date June 28 type compound fertilizer amount1200 kgha) tillering fertilizer (date July 5 type ureaamount 130 kgha) and panicle fertilizer (date August 6type urea amount 130 kgha) in this specific order All otherrecommended cultivated practices for achieving maximumgrain yield were followed

23 Sampling and Data Analysis Water samples were col-lected four times during flooding period at each stageaccording to the following sequence which was the 1st 4th7th and 10th day after being controlled Surface water wascollected by 50ml syringe and saved in polyethylene bottlewithout disturbing soil and selecting randomly Water sam-ples were analyzed for ammonium nitrogen (NH

4

+-N) andnitrate nitrogen (NO

3

minus-N) using a Shimadzu UV-2800 spec-trophotometer NH

4

+-N was determined by Nesslerrsquos reagentcolorimetric method (GB7479-87) NO

3

minus-N was deter-mined by the ultraviolet spectrophotometry method (HJT346-2007)

The N losses via subsurface drainage were calculated bymultiplying the N concentrations (both NH

4

+-N and NO3

minus-N) in the water samples and the volume of the drainage andsurface water N loads were calculated using N concentrationand surface water volume also One-way ANOVA was usedto detect the effect from N concentration to N leachingStatistical analyses of the data were performed using SPSS

3 Results

31 Dynamic Changes of NH4+-N and NO3

minus-N Concentration

311 NH4+-N and NO3

minus-N in Surface Water Figure 2 showsthe dynamic changes of NH

4

+-N and NO3

minus-N concentrationin surface water of paddy field under controlled drainageOverall a declining tendency was observed in the concentra-tion levels of NH

4

+-N and NO3

minus-N except that the NO3

minus-N concentration was increased during the tillering stagewhereas NH

4

+-N was increased later in the heading and


00

05

10

15


W1W2

Date

09

06

03

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(a)

Date

00

03

06

09

W3W4

Aug 14 Aug 17 Aug 20 Aug 23 06

04

02

00

NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(b)

Date

00

03

06

09

W5W6


02

01

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(c)

Date

00

07

14

21

W7W8


02

01

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(d)


+-N and NO3

minus-N concentration in subsurface water (a) Tillering stage (b) Jointing-booting stage (c)Heading-flowering stage (d) Milking stage

flowering stage (September 5ndash8) and early in the milky stage(September 12ndash15)

N concentrationwas relatively higher on the first day afterwaterlogging On the 10th day theNH

4

+-N concentration forW1 W2 W3 W4 W7 andW8 was reduced to 683 674382 444 550 and 627 respectively The NO

3

minus-N concentration for W3 W4 W5 W6 W7 and W8 wasreduced to 694 737 667 676 713 and 746respectively

312 NH4+-N and NO3

minus-N in Subsurface Water Figure 3presents the dynamic changes in NH

4

+-N and NO3

minus-Nconcentration in subsurface water of paddy field under con-trolled drainageThe trend of subsurface NH

4

+-N concentra-tion variety corresponded with surface water concentrationCompared with the concentration on the first day after paddyfieldwaterlogging theNH

4

+-N concentration on the 10th dayfor W1 W2 W3 W4 W7 and W8 was reduced to 646584 254 284 794 and 554 respectively

A remarkable downtrend of NO3

minus-N concentration wasobserved at the jointing and booting stage The NO

3

minus-Nconcentration on the 10th day for W3 and W4 was reducedto 455 and 374 respectively compared with that on thefirst day NO

3

minus-N concentration was relatively higher at thetillering stage mainly because of nitrification by residual Nin soil Meanwhile the change in NO

3

minus-N concentration wassmaller in other stages

32 Effect fromDrainage Intensity to N Leaching Theamountof paddy N leaching during the control period is shown inTable 3 The amount of N leaching under 4mmd leakageintensity was remarkable about two times larger than thatunder the 2mmd treatment The highest amount of NH

4

+-N and NO

3

minus-N leaching was observed at the milking andtillering stages respectively

Results of ANOVA for N concentration through leachingunder two leakage intensities are shown in Table 4 All theSig values (119901) were larger than 005 Results show that thedifference between the two conditions was not significant


Table 3 N leaching amount of controlled drainage paddy field under two leakage intensity conditions

Growth stage Tillering stage Jointing-booting stage Heading-flowering stage Milking stageLeakage intensity 2mmd 4mmd 2mmd 4mmd 2mmd 4mmd 2mmd 4mmdNH4

+-N (gsdothaminus2) 13493 26184 8625 20833 7935 20697 18513 35958NO3

minus-N (gsdothaminus2) 1086 22916 4996 12416 1976 4205 2127 4993

Table 4 ANOVA results for N concentration through leaching under two leakage intensity conditions

Factors Tillering stage Jointing-booting stage Heading-flowering stage Milking stage119865 Sig 119865 Sig 119865 Sig 119865 Sig

NH4

+-N 0007 0938 3573 0108 3703 0103 0004 0950NO3

minus-N 0246 0638 1533 0262 0127 0734 2118 0196

33 Effect of Pollution Reduction Surface water N loads andemission reduction of N under different flooding times areshown in Figures 4 and 5 N loads in surface paddy waterdeclined along with the persistence of waterlogging durationCompared with traditional drainage (drainage immediatelyafter waterlogging) PFCD (10 d) reduced N loss in surfacewater by 956 787 596 and 874 at each of the fourstages in this particular order

4 Discussion

The results indicated that N concentration in surface waterdecreased effectively when proper subsurface drainage ratein the paddy field is maintained in the waterlogging con-dition This condition is caused by several processes Thereasons for the decline in NH

4

+-N concentration includevolatilization nitrification soil adsorption crop absorptionand migration into depth Meanwhile the reasons for thedecline in NO

3

minus-N concentration include denitrificationcrop absorption leaching loss and migration into depth[30ndash34] Nitrification and denitrification are two importantmechanisms of nitrogen transform and N

2O emissions from

fields Many factors regulate these processes particularly soilwater content and temperature microorganism types andPH and so on Subsurface environment affects the activityof soil bacteria significantly The mechanisms of temperatureand soil water regime effects should be studied specifically

N concentrationwas relatively higher on the first day afterwaterlogging This phenomenon was caused by N releasedfrom surface soil which is disturbed by water-drop splashfrom irrigation or rainfall NH

4

+-N concentration was laterincreased at the heading and flowering stage (September 5ndash8) and in the early days at the milky stage (September 12ndash15)This phenomenon can explain the organic nitrogen releasedfrom the paddy field which was accelerated by scorchingweather NO

3

minus-N concentration was lower at the tilleringstage where the urea may still be in a hydrolytic status and acumulative process occurs for NH

4

+-N to nitrify into NO3

minus-N

Generally NO3

minus-N was relatively stable and was found tomigrate into aquifer heavily NH

4

+-N was difficult to removefrom underground and its conversion process into soil wascomplicated The underground environment in the paddyfield under controlled drainage was highly complex because

it involved the effects of soil moisture crop microorganismand fertilizer Therefore the mechanism of N migration andtransformation requires further research

Results of ANOVA for subsurface water N concentrationshowed that the difference between the two drainage inten-sities was not significant Wesstrom et al [35] compared theconventional drainage system and controlled drainage strat-egies through a field experiment in Southern Sweden and theexperiment results showed that the N and P losses in con-trolled drainage were lower than those in conventionaldrainage but N and P concentrations in subsurface drainagewater were revealed to have no significant differencesbetween the two drainage systems Such results were similarto ours although the conditions we compared were bothunder a controlled drainage system This suggests that the Nconcentrations were similar under two leakage conditions Nloss through drainage increases as runoff volume increasesFurthermore we consider drainage water volume as themainfactor that affects N leaching amount

As mentioned a mass of N wound was released from sur-face soil which was disturbed by irrigation or rainfall on thefirst day after waterloggingThus we should not discharge thesurface water immediately after paddy flooding In our teststhe loads ofN losses on the fourth day afterwaterloggingwereincreased at the jointing-booting and milking stages Surfacedrainage should be avoided in these conditions as well

On the contrary several disadvantages are caused by pro-longed waterlogging Waterlogging duration has remarkableeffects on crop yield For instance when the surface waterlevel is too high in the tillering stage it will cause the num-ber of tillers to reduce and lead directly to reducing the riceyield in the late stage So paddy water should be drainedat an appropriate time Rice plant manifests root hypoxiawhen it lives in the field without leakage or without being indeep water for a long time This condition goes against thephysiological metabolism of the rice plant and therefore dis-rupts photosynthesis eventually causing plant growth retar-dation and yield reduction These adverse effects can bereduced by enhancing field leakage which can increase soilventilation volume

Paddy field controlled drainage can effectively save irri-gation water and decrease nitrogen pollution emission How-ever many issues require further study such as how riceyield losses can be minimized on the basis of water saving


1st 4th 7th 10th00

04

08

12

N loads

Waterlogging duration (d)

0

4

8

12

Accumulated water consumption

Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)

(a)

1st 4th 7th 10th00

03

06

09


0

7

14

21

Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)

N loadsAccumulated water consumption

(b)

1st 4th 7th 10th00

04

08

12


Wat

er d

epth

(cm

)

0

4

8

12

N lo

ads (

kgmiddoth

aminus1)


(c)

1st 4th 7th 10th00

08

16

24


0

6

12

18

N lo

ads (

kgmiddoth

aminus1)


Wat

er d

epth

(cm

)

(d)

Figure 4 Loads of N in surface water and accumulated water consumption (a) Tillering stage (b) Jointing-booting stage (c) Heading-flowering stage (d) Milking stage The accumulated water consumption was measured by water decrease depth

W1 W2 W3 W4 W5 W6 W7 W80

1

2

3

Treatment

Emiss

ion

redu

ctio

ns (k

gmiddotha

minus1)

4 d7 d10 d

Figure 5 N emission reductions of PFCD treatments

and pollution reduction Such a problem must be assessedcomprehensively from the perspectives of surface waterdepth flooding stage and time of duration leakage intensityand other factors More tests need to be carried out in thefuture to provide a basis for decision-making We can deter-

mine the optimal drainage time through the multiobjectiveanalysis method

5 Conclusions

By analyzing N concentration and calculating the amount ofN leaching and loads of N losses we can summarize themainconclusions of this experimental study as follows

(1) The NH4

+-N and NO3

minus-N concentrations in paddywater declined along with the prolongation of water-logging duration Surface water was found to havehigher N concentration on the first day after paddyfield waterlogging at each stage and loads of N lossesincreased on the fourth day at the jointing-bootingand milking stages Thus surface drainage should beavoided in these two conditions

(2) The amount of N leaching under 4mmd leakageintensity was approximately two times larger thanthat under the 2mmd treatment Results of ANOVAfor N concentration through leaching under the twoleakage intensities showed that the difference betweensuch intensity levelswas not significantTherefore the


main factor that affects N leaching amount is seepagewater volume

(3) Loads of N losses in surface paddy water declinedwith the continuation of waterlogging durationCompared with traditional drainage controlleddrainage reduced N loss in surface water by 956787 596 and 874 at each of the four stages

Competing Interests

The authors declare that they have no competing interests

Acknowledgments

This work was financially supported by the National NaturalScience Foundation of China (Grant no 51479063) theMinistry of Water Resourcesrsquo Special Funds for ScientificResearch on Public Causes (Grant nos 201401083 and201401058) and the Scientific Research Foundation of NHRI(Grant nos Y113007 and Y113008)

References

[1] W Shao ldquoEffectiveness of water protection policy in China acase study of Jiaxingrdquo Science of the Total Environment vol 408no 4 pp 690ndash701 2010

[2] E D Ongley Z Xiaolan and Y Tao ldquoCurrent status of agri-cultural and rural non-point source pollution assessment inChinardquo Environmental Pollution vol 158 no 5 pp 1159ndash11682010

[3] H Hu and G Huang ldquoMonitoring of non-point source pollu-tions from an agriculture watershed in SouthChinardquoWater vol6 no 12 pp 3828ndash3840 2014

[4] H Y Guo X RWang and J G Zhu ldquoQuantification and indexof non-point source pollution in Taihu Lake region with GISrdquoEnvironmental Geochemistry and Health vol 26 no 2 pp 147ndash156 2004

[5] L Gao J M Zhou H Yang and J Chen ldquoPhosphorus frac-tions in sediment profiles and their potential contributions toeutrophication in Dianchi Lakerdquo Environmental Geology vol48 no 7 pp 835ndash844 2005

[6] C Le Y Zha Y Li D Sun H Lu and B Yin ldquoEutrophication oflake waters in China cost causes and controlrdquo EnvironmentalManagement vol 45 no 4 pp 662ndash668 2010

[7] J Qiao L Yang T Yan F Xue and D Zhao ldquoNitrogen fertilizerreduction in rice production for two consecutive years in theTaihu Lake areardquo Agriculture Ecosystems and Environment vol146 no 1 pp 103ndash112 2012

[8] J E Ayars E W Christen and J W Hornbuckle ldquoControlleddrainage for improved water management in arid regions irri-gated agriculturerdquo Agricultural Water Management vol 86 no1-2 pp 128ndash139 2006

[9] R W Skaggs N R Fausey and R O Evans ldquoDrainage watermanagementrdquo Journal of Soil and Water Conservation vol 67no 6 pp 167Andash172A 2012

[10] S Peng Y Luo J Xu S Khan X Jiao andWWang ldquoIntegratedirrigation and drainage practices to enhance water productivityand reduce pollution in a rice production systemrdquo Irrigation andDrainage vol 61 no 3 pp 285ndash293 2012

[11] S E Yu Z M Miao W G Xing G C Shao and Y X JiangldquoResearch advance on irrigation-drainage for rice by usingfield water level as regulation indexrdquo Journal of Irrigation andDrainage vol 29 no 2 pp 134ndash136 2010

[12] B Lu S Q Wu S E Yu et al ldquoChanges of N concentrationand effects of pollution reducing and water saving in paddyfield under controlled drainagerdquo inProceedings of the 35th IAHRWorld Congress pp 3297ndash3303 Chengdu China September2013

[13] H Y F Ng C S Tan C F Drury and J D Gaynor ldquoControlleddrainage and subirrigation influences tile nitrate loss and cornyields in a sandy loam soil in Southwestern Ontariordquo Agri-culture Ecosystems and Environment vol 90 no 1 pp 81ndash882002

[14] J W Gilliam R W Skaggs and S B Weed ldquoDrainage controlto diminish nitrate loss from agricultural fieldsrdquo Journal of Envi-ronmental Quality vol 8 no 1 pp 137ndash142 1979

[15] R O Evans J W Gilliam and R W Skaggs ldquoEffects of agri-cultural water table management on drainage qualityrdquo TechRep 237 Water Resources Research Institute of the Universityof North Carolina Raleigh NC USA 1989

[16] M A S Wahba M El-Ganainy M S Abdel-Dayem A TE F Gobran and H Kandil ldquoControlled drainage effects onwater quality under semi-arid conditions in the Western Deltaof Egyptrdquo Irrigation and Drainage vol 50 no 4 pp 295ndash3082001

[17] G Bonaiti and M Borin ldquoEfficiency of controlled drainageand subirrigation in reducing nitrogen losses from agriculturalfieldsrdquo Agricultural Water Management vol 98 no 2 pp 343ndash352 2010

[18] C F Drury C S Tan J D Gaynor T O Oloya and TW Welacky ldquoInfluence of controlled drainage-subirrigation onsurface and tile drainage nitrate lossrdquo Journal of EnvironmentalQuality vol 25 no 2 pp 317ndash324 1996

[19] I Wesstrom I Messing H Linner and J Lindstrom ldquoCon-trolled drainagemdasheffects on drain outflow and water qualityrdquoAgricultural Water Management vol 47 no 2 pp 85ndash100 2001

[20] W Luo G R Sands M Youssef J S Strock I Song and DCanelon ldquoModeling the impact of alternative drainage practicesin the northern Corn-belt with DRAINMOD-NIIrdquoAgriculturalWater Management vol 97 no 3 pp 389ndash398 2010

[21] Y F Zhang W Z Zhang and R K Shen ldquoThe study of thetransport transformation and losses of nitrogen in drainedagricultural landsrdquo Journal of Hydrodynamics Series A vol 11no 3 pp 251ndash260 1996 (Chinese)

[22] W Luo Z-H Jia S-X Fang and L Wang ldquoEffect of drainagecontrol on salt and water balance in rice fieldrdquo Journal ofHydraulic Engineering vol 37 no 5 pp 608ndash618 2006 (Chi-nese)

[23] Z H Jia W Luo S Fang N Wang and L Wang ldquoEvaluatingcurrent drainage practices and feasibility of controlled drainagein the YinNan Irrigation District Chinardquo Agricultural WaterManagement vol 84 no 1-2 pp 20ndash26 2006

[24] M-H Xiao S-E Yu G Cheng and D-L Shao ldquoTechnicalstandards of irrigation and drainage management in paddyfield of water-saving and pollution-reduction with high yieldrdquoJournal of Food Agriculture amp Environment vol 10 no 2 pp1005ndash1011 2012

[25] M-H Xiao S-E Yu Y-Y Wang and R Huang ldquoNitrogenand phosphorus changes and optimal drainage time of floodedpaddy field based on environmental factorsrdquoWater Science andEngineering vol 6 no 2 pp 164ndash177 2013


[26] S E Yu Research on Irrigation and Drainage for Rice by UsingField Water Table as Regulation Index Hohai University 2008(Chinese)

[27] G-C Shao S Deng N Liu S-E Yu M-H Wang and D-LShe ldquoEffects of controlled irrigation and drainage on growthgrain yield and water use in paddy ricerdquo European Journal ofAgronomy vol 53 pp 1ndash9 2014

[28] G Shao J Cui S E Yu et al ldquoImpacts of controlled irrigationand drainage on the yield and physiological attributes of ricerdquoAgricultural Water Management vol 149 pp 156ndash165 2015

[29] S Z Peng S S Li G L Xu and Z Wu ldquoNew water con-sumption pattern of rice under water-saving irrigationrdquo Irriga-tion and Drainage Systems vol 8 no 2 pp 97ndash108 1994

[30] T M Addiscott and D S Powlson ldquoPartitioning losses ofnitrogen fertilizer between leaching and denitrificationrdquo TheJournal of Agricultural Science vol 118 no 1 pp 101ndash107 1992

[31] B A Kliewer and J W Gilliam ldquoWater table managementeffects on denitrification and nitrous oxide evolutionrdquo SoilScience Society of America Journal vol 59 no 6 pp 1694ndash17011995

[32] M Paasonen-Kivekas T Karvonen P Vakkilainen N Sepahi JKleemola and M Teittinen ldquoField studies on controlled drain-age and recycling irrigation drainage for reduction of nutrientloading from arable landrdquoWater Science and Technology vol 33no 4-5 pp 333ndash339 1996

[33] S Y Feng and Y Q Zheng ldquoTransformations and losses ofthe agricultural nitrogen and its effects on water qualityrdquo Agro-Environmental Protection vol 6 pp 277ndash280 1996 (Chinese)

[34] C Wang ldquoExperimental study of nitrogen transportand trans-formation in soilsrdquo Advances in Water Science vol 2 pp 176ndash182 1997 (Chinese)

[35] I Wesstrom A Joel and I Messing ldquoControlled drainage andsubirrigation-a water management option to reduce non-pointsource pollution from agricultural landrdquo Agriculture Ecosys-tems and Environment vol 198 pp 74ndash82 2014

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


Table 1 Physical and chemical characteristics of topsoil (0ndash30 cm layer) in lysimeters

120579119899

120588119887

Porosity pH Organic matter Total N Available N Total P Available P() (gcm3) () (mdash) (gkg) (gkg) (mgkg) (gkg) (mgkg)2528 146 4497 697 2188 09048 2765 032 125Note 120579119899 and 120588119887 represent field moisture capacity and soil bulk density respectively

subsurface water level can prompt soil denitrification whichthen decreases the concentration of nitrate nitrogen

The PFCD technology was discovered by Chinese schol-ars in the 1990s and several experimental studies and fieldpractices have been conducted constantly in rice-plantingregions Zhang et al [21] studied the transport and loss ofnitrogen in a drainage paddy field Luo et al [22] and Jia et al[23] conducted field experiments on the effects of drainagecontrol on salt and water balance in the Yinnan irrigationdistrict Xiao et al [24 25] examined the changes in N andP of flooded paddy water systems and obtained the optimaldrainage time at each stage of growth All the results con-cluded that PFCD plays a significant role in water conserva-tion and nonpoint source pollution reduction

Two important factors for PFCD are surface water leveland waterlogging duration When the paddy surface waterlevel is too deep or when the duration of waterlogging is toolong a waterlogged disaster can occur which may then causeplant growth retardation and yield reduction On the con-trary pollution reduction and water conservation cannot beachieved when waterlogging duration is too short To achievecomprehensive benefits from environment and economicresources we must assess surface water depth flooding timeleakage intensity and other factors [26 27]

This study emphasized the environmental benefits ofdeliberate water resources utilization The paper showeddynamic changes in N concentration in surface and subsur-face paddy water analyzed the effects of leakage intensityand N leaching calculated loads of N losses through surfacedrainage and demonstrated the effects of pollution reductionand water saving through PFCD

2 Materials and Methods

21 Experimental Site This study was conducted in an exper-imental field at water-saving and agroecological experimentalplot located in JiangningCampus ofHohaiUniversity JiangsuProvince of China (Nanjing latitude 31∘571015840N longitude118∘501015840E 144m above sea level) The region has a subtrop-ical humid monsoon climate zone with an average annualevaporation of 900mm and yearly average temperature of157∘C and themaximum andminimum air temperatures are430∘C and minus140∘C respectively The mean annual rainfall is1021mm of which more than 60 of precipitation falls in therainy season and the precipitation is concentrated in May toSeptemberThe number of frost-free days is 237 per yearThetemperature precipitation and evaporation were recordeddaily by an automatic weather station (ICT Australia) in theexperimental plot

The area has been 5 years of rice-wheat rotation systemThe soil in the area is a typical permeable paddy soil The

topsoil was 0ndash30 cm in lysimeter with pH value of 697 soilbulk density was 146 gcm3 soil porosity was 4497 andfield capacitywas 2528Characteristics of topsoil are showninTable 1There are 32 fixed lysimeter test-pits (28with closedconcrete bottom 4 without bottom) with specifications forthe length times width times depth = 25m times 2m times 2m in the experimental field Those lysimeters layouts were divided into twogroups of 16 each We only employed 18 of them in thisresearch shown in Figure 1(a) Underground gallery anddrainage system are built between the two groups and amobile canopy is equipped on the ground

An integrated irrigation-drainage system (IDS) wasinstalled at the experimental field For the irrigation systemwater was supplied from an underground reservoir to everytest-pit through pipelines and the accuracy of irrigationwater volume is controlled by a computer by controlling theelectromagnetic flow valves (see Figures 1(a) and 1(c)) Watertable was changed by raising or lowing the height of a floatvalve for each treatment When the ponded water depthdropped to the lower water level irrigation water was addedwith auto-irrigation system until the upper water level limitwas reached For details of water table control structures seeFigure 1 in [28] The drainage system is located in subsurfacebelow the ground path in the middle of the test-pits (seeFigures 1(a) and 1(b)) Groundwater in the test-pits can bedischarged through artificial drainage which can controldrainage time and water volume and facilitate collection ofgroundwater samples

22 Experimental Design The variety of rice used in the2010 experiment was Japonica riceYangjing 4038 To performpaddy field water level management under different floodingconditions we designed a series of tests at the four majorstages of rice growth (tillering jointing and booting headingand flowering and milky stage in such order) The paddyfield water levels rice growth stages and controlled drainageperiods are summarized in Table 2

Eight waterlogging and controlled drainage treatments(W1ndashW8) and one treatment for comparison (CK) were usedin the experiment each with two reduplications Waterlog-ging treatments were performed in lysimeters with a closedbottom whereas comparative treatments were performed inlysimeters without a bottom Two leakage rates (2mmd and4mmd) were designed under the same flooding conditionin each stage The paddy field waterlogging process was sim-ulated after one occurrence of intensive rainfall in differentperiods The irrigation program used on comparative treat-ments was based on controlled irrigation which is an irriga-tion program for water saving [28 29]

Agricultural fertilization was conducted three times dur-ing the period of rice growthThe fertilizers appliedwere base


W1a

W1b






Collecting well

Two-way valve



NS

S

Watertank


N

N

Drainage valve

20m 25m


(a)

(b) (c)









00

05

10

15

W1W2

Date

06

04

02

00


NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(a)

Date

00

03

06

09

W3W4


08

04

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(b)

Date

00

02

04

06

W5W6


12

06

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(c)

Date

00

07

14

21

W7W8


08

04

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(d)


+-N and NO3




4


3


4


3



4

+-N and NO3


3 Results



311 NH4+-N and NO3


4

+-N and NO3


4

+-N and NO3



4



00

05

10

15


W1W2

Date

09

06

03

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(a)

Date

00

03

06

09

W3W4


04

02

00

NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(b)

Date

00

03

06

09

W5W6


02

01

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(c)

Date

00

07

14

21

W7W8


02

01

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(d)


+-N and NO3




4


3


312 NH4+-N and NO3


4

+-N and NO3


4


4




3


3


3



4

+-N and NO

3










NH4

+-N 0007 0938 3573 0108 3703 0103 0004 0950NO3

minus-N 0246 0638 1533 0262 0127 0734 2118 0196


4 Discussion


4


3


2O emissions from



4


3


4


minus-N

Generally NO3


4








1st 4th 7th 10th00

04

08

12

N loads


0

4

8

12


Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)

(a)

1st 4th 7th 10th00

03

06

09


0

7

14

21

Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)


(b)

1st 4th 7th 10th00

04

08

12


Wat

er d

epth

(cm

)

0

4

8

12

N lo

ads (

kgmiddoth

aminus1)


(c)

1st 4th 7th 10th00

08

16

24


0

6

12

18

N lo

ads (

kgmiddoth

aminus1)


Wat

er d

epth

(cm

)

(d)


W1 W2 W3 W4 W5 W6 W7 W80

1

2

3

Treatment

Emiss

ion

redu

ctio

ns (k

gmiddotha

minus1)

4 d7 d10 d




5 Conclusions


(1) The NH4

+-N and NO3






Competing Interests


Acknowledgments


References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


W1a

W1b






Collecting well

Two-way valve



NS

S

Watertank


N

N

Drainage valve

20m 25m


(a)

(b) (c)









00

05

10

15

W1W2

Date

06

04

02

00


NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(a)

Date

00

03

06

09

W3W4


08

04

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(b)

Date

00

02

04

06

W5W6


12

06

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(c)

Date

00

07

14

21

W7W8


08

04

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(d)


+-N and NO3




4


3


4


3



4

+-N and NO3


3 Results



311 NH4+-N and NO3


4

+-N and NO3


4

+-N and NO3



4



00

05

10

15


W1W2

Date

09

06

03

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(a)

Date

00

03

06

09

W3W4


04

02

00

NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(b)

Date

00

03

06

09

W5W6


02

01

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(c)

Date

00

07

14

21

W7W8


02

01

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(d)


+-N and NO3




4


3


312 NH4+-N and NO3


4

+-N and NO3


4


4




3


3


3



4

+-N and NO

3










NH4

+-N 0007 0938 3573 0108 3703 0103 0004 0950NO3

minus-N 0246 0638 1533 0262 0127 0734 2118 0196


4 Discussion


4


3


2O emissions from



4


3


4


minus-N

Generally NO3


4








1st 4th 7th 10th00

04

08

12

N loads


0

4

8

12


Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)

(a)

1st 4th 7th 10th00

03

06

09


0

7

14

21

Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)


(b)

1st 4th 7th 10th00

04

08

12


Wat

er d

epth

(cm

)

0

4

8

12

N lo

ads (

kgmiddoth

aminus1)


(c)

1st 4th 7th 10th00

08

16

24


0

6

12

18

N lo

ads (

kgmiddoth

aminus1)


Wat

er d

epth

(cm

)

(d)


W1 W2 W3 W4 W5 W6 W7 W80

1

2

3

Treatment

Emiss

ion

redu

ctio

ns (k

gmiddotha

minus1)

4 d7 d10 d




5 Conclusions


(1) The NH4

+-N and NO3






Competing Interests


Acknowledgments


References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00

05

10

15

W1W2

Date

06

04

02

00


NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(a)

Date

00

03

06

09

W3W4


08

04

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(b)

Date

00

02

04

06

W5W6


12

06

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(c)

Date

00

07

14

21

W7W8


08

04

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(d)


+-N and NO3




4


3


4


3



4

+-N and NO3


3 Results



311 NH4+-N and NO3


4

+-N and NO3


4

+-N and NO3



4



00

05

10

15


W1W2

Date

09

06

03

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(a)

Date

00

03

06

09

W3W4


04

02

00

NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(b)

Date

00

03

06

09

W5W6


02

01

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(c)

Date

00

07

14

21

W7W8


02

01

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(d)


+-N and NO3




4


3


312 NH4+-N and NO3


4

+-N and NO3


4


4




3


3


3



4

+-N and NO

3










NH4

+-N 0007 0938 3573 0108 3703 0103 0004 0950NO3

minus-N 0246 0638 1533 0262 0127 0734 2118 0196


4 Discussion


4


3


2O emissions from



4


3


4


minus-N

Generally NO3


4








1st 4th 7th 10th00

04

08

12

N loads


0

4

8

12


Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)

(a)

1st 4th 7th 10th00

03

06

09


0

7

14

21

Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)


(b)

1st 4th 7th 10th00

04

08

12


Wat

er d

epth

(cm

)

0

4

8

12

N lo

ads (

kgmiddoth

aminus1)


(c)

1st 4th 7th 10th00

08

16

24


0

6

12

18

N lo

ads (

kgmiddoth

aminus1)


Wat

er d

epth

(cm

)

(d)


W1 W2 W3 W4 W5 W6 W7 W80

1

2

3

Treatment

Emiss

ion

redu

ctio

ns (k

gmiddotha

minus1)

4 d7 d10 d




5 Conclusions


(1) The NH4

+-N and NO3






Competing Interests


Acknowledgments


References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00

05

10

15


W1W2

Date

09

06

03

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(a)

Date

00

03

06

09

W3W4


04

02

00

NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(b)

Date

00

03

06

09

W5W6


02

01

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(c)

Date

00

07

14

21

W7W8


02

01

00NH

4

+-N

(mgmiddot

Lminus1)

NO

3

minus-N

(mgmiddot

Lminus1)

(d)


+-N and NO3




4


3


312 NH4+-N and NO3


4

+-N and NO3


4


4




3


3


3



4

+-N and NO

3










NH4

+-N 0007 0938 3573 0108 3703 0103 0004 0950NO3

minus-N 0246 0638 1533 0262 0127 0734 2118 0196


4 Discussion


4


3


2O emissions from



4


3


4


minus-N

Generally NO3


4








1st 4th 7th 10th00

04

08

12

N loads


0

4

8

12


Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)

(a)

1st 4th 7th 10th00

03

06

09


0

7

14

21

Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)


(b)

1st 4th 7th 10th00

04

08

12


Wat

er d

epth

(cm

)

0

4

8

12

N lo

ads (

kgmiddoth

aminus1)


(c)

1st 4th 7th 10th00

08

16

24


0

6

12

18

N lo

ads (

kgmiddoth

aminus1)


Wat

er d

epth

(cm

)

(d)


W1 W2 W3 W4 W5 W6 W7 W80

1

2

3

Treatment

Emiss

ion

redu

ctio

ns (k

gmiddotha

minus1)

4 d7 d10 d




5 Conclusions


(1) The NH4

+-N and NO3






Competing Interests


Acknowledgments


References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of








NH4

+-N 0007 0938 3573 0108 3703 0103 0004 0950NO3

minus-N 0246 0638 1533 0262 0127 0734 2118 0196


4 Discussion


4


3


2O emissions from



4


3


4


minus-N

Generally NO3


4








1st 4th 7th 10th00

04

08

12

N loads


0

4

8

12


Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)

(a)

1st 4th 7th 10th00

03

06

09


0

7

14

21

Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)


(b)

1st 4th 7th 10th00

04

08

12


Wat

er d

epth

(cm

)

0

4

8

12

N lo

ads (

kgmiddoth

aminus1)


(c)

1st 4th 7th 10th00

08

16

24


0

6

12

18

N lo

ads (

kgmiddoth

aminus1)


Wat

er d

epth

(cm

)

(d)


W1 W2 W3 W4 W5 W6 W7 W80

1

2

3

Treatment

Emiss

ion

redu

ctio

ns (k

gmiddotha

minus1)

4 d7 d10 d




5 Conclusions


(1) The NH4

+-N and NO3






Competing Interests


Acknowledgments


References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


1st 4th 7th 10th00

04

08

12

N loads


0

4

8

12


Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)

(a)

1st 4th 7th 10th00

03

06

09


0

7

14

21

Wat

er d

epth

(cm

)

N lo

ads (

kgmiddoth

aminus1)


(b)

1st 4th 7th 10th00

04

08

12


Wat

er d

epth

(cm

)

0

4

8

12

N lo

ads (

kgmiddoth

aminus1)


(c)

1st 4th 7th 10th00

08

16

24


0

6

12

18

N lo

ads (

kgmiddoth

aminus1)


Wat

er d

epth

(cm

)

(d)


W1 W2 W3 W4 W5 W6 W7 W80

1

2

3

Treatment

Emiss

ion

redu

ctio

ns (k

gmiddotha

minus1)

4 d7 d10 d




5 Conclusions


(1) The NH4

+-N and NO3






Competing Interests


Acknowledgments


References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




Competing Interests


Acknowledgments


References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Documents

Research Article The Effects of Controlled Drainage on N